There has been talks about possible presence of glyphosate and other pesticides in tubers such as potato.

I was informed by some that potato being grown some places in Canada might be desiccated by glyphosate prior to harvesting. But according to data received from CFIA, potato were not tested for glyphosate, and the word potato comes up sparingly in the items tested which were processed meals that contained potato. Potato might not have been the main ingredient in those products and the presence of glyphosate was not noted to be high or consistent. So I would say that the CFIA results were not conclusive that potato posed a serious threat to glyphosate poisoning to people.

Anyhow, I asked Anthony Samsel. This is what he said:

necrotic lesions

(Above pictures, as well as the rest, are new to me. I have not seen such potato either in the store or in my backyard. I guess such items are removed before potatoes reach the store shelves. I might not have them because I do not use glyphosate or any industrial pesticide in my residence or garden.)

This is crippled shoot (at left) formation from the potato eyes called Cauliflower formation and is a telltale sign of glyphosate application to the field …

This is tuber cracking (at right) caused by glyphosate exposure from spray drift.

…. most potatoes have residues of herbicides and fungicides such as the fungicide Chlorothalonil… which never should have been allowed into the food supply.  This fungicide causes mammalian embryo fatalities and reductions in live fetuses…  Animal studies show that Chlorothalonil is a probable carcinogen…..
Anthony

The images and the text in blue are from scientist Anthony Samsel of USA. I have never seen such potato either but can understand why or how this might happen.

Meanwhile I did check the issue of Chlorthalonil in potato, among items tested by CFIA. There are more than 2,500 samples of potato tested by CFIA from 2008 till 2016 for presence of Chlorothalonil. Out of them all, only four samples had any chlorothalonil.

The above table shows some of the details available from the only samples that contained Chlorothalonil. For some reason, just one sample, the one on top, representing fresh potato from from the US contained over 3,700 ppb of Chlorothalonil and was in violation. The others contained less than 3 ppb, the last one was declared as organic.

The table is also the link to the full downloadable file of over 2,500 tests done on potato to find Chlorothalonil, by CFIA, between 2008 and 2016.

This is also included in the book Poison Foods of North America.